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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: David Woodhouse <dwmw2@infradead.org>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"KarimAllah Ahmed" <karahmed@amazon.de>,
	linux-kernel@vger.kernel.org, "Andi Kleen" <ak@linux.intel.com>,
	"Andrea Arcangeli" <aarcange@redhat.com>,
	"Andy Lutomirski" <luto@kernel.org>,
	"Arjan van de Ven" <arjan@linux.intel.com>,
	"Ashok Raj" <ashok.raj@intel.com>,
	"Asit Mallick" <asit.k.mallick@intel.com>,
	"Borislav Petkov" <bp@suse.de>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Dave Hansen" <dave.hansen@intel.com>,
	"H . Peter Anvin" <hpa@zytor.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Janakarajan Natarajan" <Janakarajan.Natarajan@amd.com>,
	"Joerg Roedel" <joro@8bytes.org>,
	"Jun Nakajima" <jun.nakajima@intel.com>,
	"Laura Abbott" <labbott@redhat.com>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Masami Hiramatsu" <mhiramat@kernel.org>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Tim Chen" <tim.c.chen@linux.intel.com>,
	"Tom Lendacky" <thomas.lendacky@amd.com>,
	kvm@vger.kernel.org, x86@kernel.org
Subject: Re: [RFC 05/10] x86/speculation: Add basic IBRS support infrastructure
Date: Wed, 24 Jan 2018 10:10:49 +0100	[thread overview]
Message-ID: <20180124091049.GB12100@kroah.com> (raw)
In-Reply-To: <1516784541.13558.90.camel@infradead.org>

On Wed, Jan 24, 2018 at 09:02:21AM +0000, David Woodhouse wrote:
> On Wed, 2018-01-24 at 09:47 +0100, Peter Zijlstra wrote:
> > Typically tglx likes to use x86_match_cpu() for these things; see also
> > commit: bd9240a18edfb ("x86/apic: Add TSC_DEADLINE quirk due to
> > errata").
> 
> Thanks, will fix. I think we might also end up in whitelist mode,
> adding "known good" microcodes to the list as they get released or
> retroactively blessed.
> 
> I would really have liked a new bit in IA32_ARCH_CAPABILITIES to say
> that it's safe, but that's not possible for *existing* microcode which
> actually turns out to be OK in the end.
> 
> That means the whitelist ends up basically empty right now. Should I
> add a command line parameter to override it? Otherwise we end up having
> to rebuild the kernel every time there's a microcode release which
> covers a new CPU SKU (which is why I kind of hate the whitelist, but
> Arjan is very insistent...)

Ick, no, whitelists are a pain for everyone involved.  Don't do that
unless it is absolutely the only way it will ever work.

Arjan, why do you think this can only be done as a whitelist?

It's much easier to just mark the "bad" microcode versions as those
_should_ be a much smaller list that Intel knows about today.  And of
course, any future microcode updates will not be "bad" because they know
how to properly test for this now before they are released :)

thanks,

greg k-h

  reply	other threads:[~2018-01-24  9:10 UTC|newest]

Thread overview: 143+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-20 19:22 [RFC 00/10] Speculation Control feature support KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 01/10] x86/speculation: Add basic support for IBPB KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 02/10] x86/kvm: Add IBPB support KarimAllah Ahmed
2018-01-20 20:18   ` Woodhouse, David
2018-01-22 18:56   ` Jim Mattson
2018-01-22 19:31     ` Jim Mattson
2018-01-20 19:22 ` [RFC 03/10] x86/speculation: Use Indirect Branch Prediction Barrier in context switch KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 04/10] x86/mm: Only flush indirect branches when switching into non dumpable process KarimAllah Ahmed
2018-01-20 21:06   ` Woodhouse, David
2018-01-22 18:29     ` Tim Chen
2018-01-21 11:22   ` Peter Zijlstra
2018-01-21 12:04     ` David Woodhouse
2018-01-21 14:07       ` H.J. Lu
2018-01-22 10:19       ` Peter Zijlstra
2018-01-22 10:23         ` David Woodhouse
2018-01-21 16:21     ` Ingo Molnar
2018-01-21 16:25       ` Arjan van de Ven
2018-01-21 22:20       ` Woodhouse, David
2018-01-29  6:35     ` Jon Masters
2018-01-29 14:07       ` Peter Zijlstra
2018-01-20 19:22 ` [RFC 05/10] x86/speculation: Add basic IBRS support infrastructure KarimAllah Ahmed
2018-01-21 14:31   ` Thomas Gleixner
2018-01-21 14:56     ` Borislav Petkov
2018-01-22  9:51       ` Peter Zijlstra
2018-01-22 12:06         ` Borislav Petkov
2018-01-22 13:30           ` Greg Kroah-Hartman
2018-01-22 13:37             ` Woodhouse, David
2018-01-21 15:25     ` David Woodhouse
2018-01-23 20:58     ` David Woodhouse
2018-01-23 22:43       ` Johannes Erdfelt
2018-01-24  8:47       ` Peter Zijlstra
2018-01-24  9:02         ` David Woodhouse
2018-01-24  9:10           ` Greg Kroah-Hartman [this message]
2018-01-24 15:09             ` Arjan van de Ven
2018-01-24 15:18               ` David Woodhouse
2018-01-24  9:34           ` Peter Zijlstra
2018-01-24 10:49           ` Henrique de Moraes Holschuh
2018-01-24 12:30             ` David Woodhouse
2018-01-24 12:14         ` David Woodhouse
2018-01-24 12:29           ` Peter Zijlstra
2018-01-24 12:58             ` David Woodhouse
2018-01-29 20:14   ` [RFC,05/10] " Eduardo Habkost
2018-01-29 20:17     ` David Woodhouse
2018-01-29 20:42       ` Eduardo Habkost
2018-01-29 20:44         ` Arjan van de Ven
2018-01-29 21:02           ` David Woodhouse
2018-01-29 21:37             ` Jim Mattson
2018-01-29 21:50               ` Eduardo Habkost
2018-01-29 22:12                 ` Jim Mattson
2018-01-30  1:22                   ` Eduardo Habkost
2018-01-29 22:25                 ` Andi Kleen
2018-01-30  1:37                   ` Eduardo Habkost
2018-01-29 21:37             ` Andi Kleen
2018-01-29 21:44             ` Eduardo Habkost
2018-01-29 22:10               ` Konrad Rzeszutek Wilk
2018-01-30  1:12                 ` Eduardo Habkost
2018-01-30  0:23             ` Linus Torvalds
2018-01-30  1:03               ` Jim Mattson
2018-01-30  3:13                 ` Andi Kleen
2018-01-31 15:03                   ` Paolo Bonzini
2018-01-31 15:07                     ` Dr. David Alan Gilbert
2018-01-30  1:32               ` Arjan van de Ven
2018-01-30  3:32                 ` Linus Torvalds
2018-01-30 12:04                   ` Eduardo Habkost
2018-01-30 13:54                   ` Arjan van de Ven
2018-01-30  8:22               ` David Woodhouse
2018-01-30 11:35               ` David Woodhouse
2018-01-30 11:56               ` Dr. David Alan Gilbert
2018-01-30 12:11               ` Christian Borntraeger
2018-01-30 14:46                 ` Christophe de Dinechin
2018-01-30 14:52                   ` Christian Borntraeger
2018-01-30 14:56                     ` Christophe de Dinechin
2018-01-30 15:33                       ` Christian Borntraeger
2018-01-30 20:46               ` Alan Cox
2018-01-31 10:05                 ` Christophe de Dinechin
2018-01-31 10:15                   ` Thomas Gleixner
2018-01-31 11:04                     ` Dr. David Alan Gilbert
2018-01-31 11:52                       ` Borislav Petkov
2018-01-31 12:30                         ` Dr. David Alan Gilbert
2018-01-31 13:18                           ` Borislav Petkov
2018-01-31 14:04                             ` Dr. David Alan Gilbert
2018-01-31 14:44                               ` Eduardo Habkost
2018-01-31 16:28                                 ` Borislav Petkov
2018-01-31 11:07                     ` Christophe de Dinechin
2018-01-31 15:00                     ` Eduardo Habkost
2018-01-31 15:11                     ` Arjan van de Ven
2018-01-31 10:03   ` [RFC 05/10] " Christophe de Dinechin
2018-01-20 19:22 ` [RFC 06/10] x86/speculation: Add inlines to control Indirect Branch Speculation KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 07/10] x86: Simplify spectre_v2 command line parsing KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 08/10] x86/idle: Control Indirect Branch Speculation in idle KarimAllah Ahmed
2018-01-20 19:23 ` [RFC 09/10] x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation KarimAllah Ahmed
2018-01-21 19:14   ` Andy Lutomirski
2018-01-23 16:12     ` Tom Lendacky
2018-01-23 16:20       ` Woodhouse, David
2018-01-23 22:37         ` Tom Lendacky
2018-01-23 22:49           ` Andi Kleen
2018-01-23 23:14             ` Woodhouse, David
2018-01-23 23:22               ` Andi Kleen
2018-01-24  0:47               ` Tim Chen
2018-01-24  1:00                 ` Andy Lutomirski
2018-01-24  1:22                   ` David Woodhouse
2018-01-24  1:59                   ` Van De Ven, Arjan
2018-01-24  3:25                     ` Andy Lutomirski
2018-01-21 19:34   ` Linus Torvalds
2018-01-21 20:28     ` David Woodhouse
2018-01-21 21:35       ` Linus Torvalds
2018-01-21 22:00         ` David Woodhouse
2018-01-21 22:27           ` Linus Torvalds
2018-01-22 16:27             ` David Woodhouse
2018-01-23  7:29               ` Ingo Molnar
2018-01-23  7:53                 ` Ingo Molnar
2018-01-23  9:27                   ` Ingo Molnar
2018-01-23  9:37                     ` David Woodhouse
2018-01-23 15:01                     ` Dave Hansen
2018-01-23  9:30                   ` David Woodhouse
2018-01-23 10:15                     ` Ingo Molnar
2018-01-23 10:27                       ` David Woodhouse
2018-01-23 10:44                         ` Ingo Molnar
2018-01-23 10:57                           ` David Woodhouse
2018-01-23 10:23                     ` Ingo Molnar
2018-01-23 10:35                       ` David Woodhouse
2018-02-04 18:43                       ` Thomas Gleixner
2018-02-04 20:22                         ` David Woodhouse
2018-02-06  9:14                         ` David Woodhouse
2018-01-25 16:19                     ` Mason
2018-01-25 17:16                       ` Greg Kroah-Hartman
2018-01-29 11:59                         ` Mason
2018-01-24  0:05                 ` Andi Kleen
2018-01-23 20:16       ` Pavel Machek
2018-01-20 19:23 ` [RFC 10/10] x86/enter: Use IBRS on syscall and interrupts KarimAllah Ahmed
2018-01-21 13:50   ` Konrad Rzeszutek Wilk
2018-01-21 14:40     ` KarimAllah Ahmed
2018-01-21 17:22     ` Dave Hansen
2018-01-21 14:02 ` [RFC 00/10] Speculation Control feature support Konrad Rzeszutek Wilk
2018-01-22 21:27   ` David Woodhouse
2018-01-29 22:29 [RFC,05/10] x86/speculation: Add basic IBRS support infrastructure David Dunn
2018-01-29 22:41 ` Andi Kleen
2018-01-29 22:49   ` Jim Mattson
2018-01-30  1:10     ` Eduardo Habkost
2018-01-30  1:20       ` David Dunn
2018-01-30  1:30         ` Eduardo Habkost
2018-01-29 23:51 ` Fred Jacobs
2018-01-30  1:08 ` Eduardo Habkost

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